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Talktime is generally higher in GSM phones due to the pulse nature of transmission. The availability of Subscriber Identity Modules allows users to switch networks and handsets at will, aside from a subsidy lock. GSM covers virtually all parts of the world so international roaming is not a problem.
These phones include combination of GSM and CDMA technology. They can be used as a GSM or CDMA phone according to the user's preference. These handsets are also called global phones. An example of this is the Samsung SCH-A790. These dual-mode handsets are compatible with both GSM and CDMA networks and are essentially two phones in one device.
However, unlike TDMA, there are no time slots, and all CDMA radios can be active all the time to deliver up to 14.4 kbit/s data transmission speeds. With the evolution of CDMA to CDMA2000 and 1xRTT, the use of IS-95 CDMA Circuit Switched Data declined in favour of the faster data transmission speeds available with the newer technologies.
The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation digital cellular networks used by mobile devices such as mobile phones and tablets. GSM is also a trade mark owned by the GSM Association. [2] "
Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel.
Some multi-mode phones can operate on analog networks as well (for example, dual band, tri-mode: AMPS 800 / CDMA 800 / CDMA 1900). For a GSM phone, dual-band usually means 850 / 1900 MHz in the United States and Canada, 900 / 1800 MHz in Europe and most other countries. Tri-band means 850 / 1800 / 1900 MHz or 900 / 1800 / 1900 MHz.
GSM/UMTS were the most widespread 2G/3G wireless standards worldwide. Most countries used only the GSM family. A few countries, including China, the United States, Canada, Ukraine, Trinidad and Tobago, India, South Korea and Japan, used both standards. 3GPP2 had its last activity in 2013, [2] and the group has been dormant ever since.
In Russia and some other countries, local carriers received licenses for 450 MHz frequency to provide CDMA mobile coverage area. Many GSM phones support three bands (900/1,800/1,900 MHz or 850/1,800/1,900 MHz) or four bands (850/900/1,800/1,900 MHz), and are usually referred to as tri-band and quad-band phones, or world phones; with such a ...